1. Field of the Invention
The present invention relates to an electron emission element.
2. Related Background Art
There are already known various electron emission elements, such as an element utilizing an avalanche phenomenon of a PN junction, one utilizing electron injection into a P-layer of a PN junction under forward bias, one having a thin insulator sandwiched between metal layers (MIM structure), and ones utilizing electric field emission or surface conduction.
However, in these known elements, in which electrons of high energy are electrically generated and emitted, the electron emission can only be controlled electrically, and it has not been possible to correlate the electron emission with light.